From Ad Hoc to ICEBERG: differences in two wireless network environments

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From Ad Hoc to ICEBERG differences in two
wireless network environments

• Computer Science and Engineering Department
• University of Minnesota
• Wireless Networking Seminar

Zhigang Gong gong_at_cs.umn.edu August 9, 2002
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Outline

• Ad Hoc
• What is ad hoc network?
• Why ad hoc network?
• What are the interesting research topics?
• ICEBERG
• What is ICEBERG?
• Why study ICEBERG?
• How can we take it further?

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What are Ad Hoc Networks

• In Latin, ad hoc means "for this," further
  meaning "for this purpose only.
• An ad-hoc network is a LAN or other small
  network, especially one with wireless
  connections, in which some of the network devices
  are part of the network only for the duration of
  a communications session or, in the case of
  mobile or portable devices, while in some close
  proximity to the rest of the network.

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Definition for Mobile Ad-hoc

• A "mobile ad hoc network" (MANET) is an
  autonomous system of mobile routers (and
  associated hosts) connected by wireless
  links--the union of which form an arbitrary
  graph. The routers are free to move randomly and
  organize themselves arbitrarily thus, the
  network's wireless topology may change rapidly
  and unpredictably. Such a network may operate in
  a standalone fashion, or may be connected to the
  larger Internet. -------- IETF

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Characteristics of ad hoc wireless network

• Autonomous (no infrastructure !)
• Wireless link based (bandwidth constraint)
• Dynamic topology (Due to movement or entering
  sleep mode)
• Rely on batteries for energy (Power-constraint)
• Limited physical security

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Why ad hoc wireless networking?

• Technical side
• wireless devices need to be connected
• increased performance/cost ratio on devices
• Internet compatible standards-based wireless
  systems
• Market side
• mobile computing wearable computing military
  applications disaster recovery robot data
  acquisition

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Research Challenges (I)

• MAC layer problems
• Link layer reliability
• QoS at MAC layer
• Power conservation
• Network layer problems Mobile IP
• Routing
• QoS
• Power conserving
• Multicast

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Research Challenges (II)

• Transport layer problems (TCP over Ad hoc)
• End-to-end reliability?
• Congestion control?
• QoS?
• Application layer
• Security?
• QoS?
• Inter-layer interactions
• Internetworking with internet

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Main problem Routing

• Standard (Mobile) IP needs an infrastructure
• Home Agent/Foreign Agent in the fixed network
• DNS, routing etc. are not designed for mobility
• No infrastructure in Ad hoc networks
• Main topic routing
• no default router available
• every host (node) should be able to forward
  packets

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Routing in an ad-hoc network
N1
N1
N2
N3
N2
N3
N4
N4
N5
N5
good link weak link
time t1
time t2
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Traditional routing algorithms

• Distance Vector
• periodic exchange of messages with all physical
  neighbors that contain information about who can
  be reached at what distance
• selection of the shortest path if several paths
  available
• Link State
• periodic notification of all routers about the
  current state of all physical links
• router get a complete picture of the network

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Problems of traditional routing algorithms

• Dynamic of the topology
• frequent changes of connections, connection
  quality, participants
• Limited performance of mobile systems
• periodic updates of routing tables need energy
  without contributing to the transmission of user
  data, sleep modes difficult to realize
• limited bandwidth of the system is reduced even
  more due to the exchange of routing information
• Problem protocols have been designed for fixed
  networks with infrequent changes and typically
  assume symmetric links

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Routing (Unicast)

• Table Driven DSDV, WRP, etc
• On-demand Driven AODV, TORA, DSR, ABR, SSR,
• Zone Routing Protocol (ZRP)

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DSDV (Destination Sequenced Distance Vector)

• Expansion of distance vector routing
• Sequence numbers for all routing updates
• assures in-order execution of all updates
• avoids loops and inconsistencies
• Decrease of update frequency
• store time between first and best announcement of
  a path
• inhibit update if it seems to be unstable (based
  on the stored time values)

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Dynamic source routing (DSR)

• Split routing into discovering a path and
  maintaining a path
• Discover a path
• only if a path for sending packets to a certain
  destination is needed and no path is currently
  available
• Maintaining a path
• only while the path is in use one has to make
  sure that it can be used continuously
• No periodic updates needed!

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Dynamic Source Routing Internet-Draft

• Characteristics
• On-demand
• Unidirectional links and asymmetric routes are
  supported
• Route Discovery
• S-D route is included in the header of each
  packet.
• Nodes forwarding or overhearing data packets may
  cache multiple routes for any D for future use
  (uni-directional?)
• Route Maintenance on-demand
• Link failure detection MAC layer (802.11) or
  Passive ACK or clear request for ACK
• Link ERR is propagated to source
• Use an cached new route or rediscover

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Dynamic Load-Aware Routing

• On-demand, backward learning
• S floods REQ, D choose route by-- Total buffered
  packets, Average buffered packets, or Least
  number of congested routers
• D detects over-loaded route dynamically and
  initiates route-setup procedure to S.
• Load information in I is piggybacked periodically
  on data packets
• When link failure, the upstream I sends ERR to S
  and removes its entry. S initiates new route
  setup procedure.
• I does not reply REP even it knows a route to D

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Mitigating routing misbehavior

• It is impossible to build a perfect network
• Routing denial of service
• Unexpected events, bugs, etc.
• Incorporate tools within the network to detect
  and report on misbehavior
• Route only through trusted nodes
• Requires a trust relationship
• Requires key distribution
• Trusted nodes may still be overloaded or broken
  or compromised
• Untrusted nodes might perform well
• Detect and isolate misbehaving nodes
• Watchdog detects the nodes
• Pathrater avoids routing packets through these
  nodes

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Routing (Multicast)

• Multicast is still a hot topic even in Internet
• In Ad Hoc, besides of those problems in
  traditional Internet, such as congestion control,
  routing for multicast is another big problem

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Other researches on Routing

• QoS support routing
• Power conserving routing

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ICEBERG

• http//iceberg.cs.berkeley.edu/
• ICEBERG Internet-based core for CEllular
  networks BEyond the thiRd Generation
• Internet-based integration of telephony and data
  services spanning diverse access networks
• Leverage Internets low cost of entry for service
  creation, provision, deployment and integration

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Why ICEBERG

• 3G will enable many communication devices and
  networks diversity
• Mobility for transparent information access
• New applications audio, video, multimedia

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Design Goals

• Potentially Any Network Services (PANS)
• Network and device independent
• Personal Mobility
• person as communication endpoint requires a
  single identity for an individual - iUID
• Service Mobility
• seamless mobility across different devices in the
  middle of a service session
• Easy Service Creation and Customization
• Scalability, Availability and Fault Tolerance
• Operation in the Wide Area
• Security, Authentication and Privacy

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ICEBERG Architecture Overview
Access Network Plane
ICEBERG Network Plane
Clearing House
ISP Plane
ISP1
ISP2
ISP3
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ICEBERG Components

• ICEBERG Access Point (IAP)
• A gateway serves as a bridge
• Call Agent (CA)
• call setup and control
• Name Mapping Service (NMS)
• mapping between communication endpoint and the
  iUID
• Preference Registry (PR)
• stores user profile
• Personal Activity Coordinator (PAC)
• tracks dynamic info of a person that is of her
  interest
• Automatic Path Creation Service (APC)
• establishes and manipulates data flow

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iPOP on Cluster Computing Platforms

• Ninja Base and Active Service Platform (AS1)
• Clusters of commodity PCs interconnected by a
  high-speed SAN, acting as a single L-S computer
• mask away cluster management problems
• Load balancing, availability, failure management
• Ninja highly available service initiation
• Redirector stub
• Good for long running services such as web
  servers
• AS1 fault tolerant service session
• Client heartbeat with session state
• Good for session-based services such as video
  conferencing

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An Illustration
Bob
Alice
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PR
NMS
PR
NMS
IAP
IAP
Clearing House
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Whats their difference?

• ICEBERG is an integrated service architecture to
  link any digital network with the Internet.
• Ad Hoc is in the wireless network domain.
• Put them together, some amazing application may
  be available.